Characters: There is wide latitudinal variation in this species. In subtropical localities it is usually solitary, flat and less than 60 millimetres diameter. In the tropics it is larger and sometimes colonial. Septa slope up from the columella to an indistinct wall then costae slope down to the periphery. This gives the fleshy mantle of the polyps a distinctive concentric texture. Secondary centres occur near the colony centre and also around the periphery. Septo-costae are sturdy, with large blunt teeth. Colour: Usually dark green or tan. Similar species: Scolymia australis, which is much smaller but juveniles may be indistinguishable. Habitat: Most reef environments. Abundance: Usually uncommon, rare in the south-west Indian Ocean.